I am a huge fan of both How to Train your Dragon, and Firefly. I wanted to do a mashup of the two and emphasize the playfulness of Toothless by having him chewing on Jayne Cobb's hat.
The line "You can't take the sky from me." from the theme song of Firefly really fits for Toothless. I think Toothless would totally be a Brown Coat. :)

Mal: Try to see past what she is, and on to what she can be.
Zoe: What's that, sir?
Mal: Freedom, is what.
Mal: We're still flying.
Simon: That's not much.
Mal: It's enough.
Everyone's favorite Captain Tightpants, Malcolm Reynolds.